Thank you both for putting up with my questions! (and have a couple more below).
You can set desktop with ArcadeOSD (comes with groovymame & VMM package). You can also set desktop with display manager, but ArcadeOSD is better..
So I launched ArcadeOSD, hit 2 to make it switch to the 15khz monitor (have a 4K HDMI monitor running as well), 'Attach OSD to current monitor', then I choose a resolution, and selected 'Set as Desktop mode'. I tried EVERY single resolution and the desktop still flickers worse than I've ever seen it before (even with 480i consoles). This simply doesn't make sense to me because the games themselves don't flicker (so if I choose a 320x240 - or the super-resolution version of that - 240p, this looks PERFECT on the monitor...but when showing the desktop it looks horrible). I also tried this on, no joke, 10 different CRT's (everything from Sony PVM/BVM's, to consumer TV's with a RGBS to YPbPr converter).
Directly edit the relevant ["all killer, no filler"].ini file to include the variants you want. You must have installed it somewhere? I expect it'll be in a subfolder of your groovymame install directory, maybe "category" or "folders" or even "dats".
This game (and others with this problem), don't have an individual .zip because they're merged sets, so every version of a game is in the one .zip file. As I went through more games last night, I noticed (when still using the all killer no filler game lists) that there was many which upon launching the game it gave me an option screen of which version I wanted to load (Japan, USA, Taiwan, etc. different versions), BUT this one game crimefght doesn't give me the option to load crimefghtu, so I can't play the 4-player version of it. Anything to do or just download that single (split) ROM if I can find it?
**EDIT** Found out how to do this if it helps anybody: when you choose the sub-folder the All Kill No Filler list is opening you can select to show clones (or not), this was default turned OFF for the "Multi" game list, turned it on and I can now see the correct 4-player ROM (from that merged rom) and play it.
Edit mame.ini, set the relevant rotate options there
When I first tried to get the horizontal games to play natively (i.e. on a TATE'd monitor, and not rotated to fit my regular orientation one) I tried EVERY single option of 1's and 0's in mame.ini to get it to work - nothing worked. Only making the vertical.ini with "rotate 0" worked (found that tip online after about 2 hours of trying everything else). So if I were to try it this way, which lines in mame.ini should I edit (and should I remove that vertical.ini file?)?
4) In order to handle vertical monitors, instead of using the MAME's rotation options, use GM's -orientation option. Set either -orientation rotate_r or -orientation rotate_l.
Would this have to be set on a per-game basis (I'm launching all games through MAME's built in front-end)? And would I be able to set it in the MAME frontend? Or is this for launching a single game from command line like "mame64 avengers -orientation rotate_r" (or whatever is the correct way to launch from command line - I've never really done that much).
Besides Avengers, for others which give me this problem I've been able to either go into the dipswitches, the F2 game setup/config menu, or from the Video Options and it's been working pretty well - just a couple which I wasn't able to fix this way.
For new questions I came across last night:6.) Is there a way to skip loading screens, ROM checks? Fast forward is only 120-130%... some of these ROM checks and whatnot can literally take a a minute or two (which kinda makes the kids --ok, me too
-- want to pull their hair out while they're waiting). The extremely long Raiden Fighters "999 Now Updating” countdown is extremely annoying (at least it only has to do that once...unless you exit out of it, and it corrupts it, then you can't launch the game again and spend a half hour googling how/where that corrupted data is stored to delete it and then again have to wait 999 seconds for it to rebuild
7.) I have a handful of games switching from 480i/60i to 575/50i (NTSC/PAL?) like Flying Shark )took a video of that happening it was so weird), and it does this constantly and won't stop. Some monitors are ok, where others freak out like this. They're all Sony PVM/BVM monitors, and can switch from NTSC to PAL resolution. Maybe using the "Arcade 15.7khz - standard resolutions" is giving too wide of a frequency range (or whatever), and those particular monitors can't handle it? Better off using the standard 15Khz modelines through VMMaker instead? (honestly not too many games at all, was just wondering)
8.) Is there a way to normalize sound? It’s literally ALL over the place - from screaming loud, to barely a whisper. Many of the problematic (WAY too soft) games, have a volume slider, and it's always set to 0 (or maxed out - can only go softer).
9.) For games where this isn't an option to add rapid fire for a certain button, is there a way to turn on rapid fire for every games (mostly SHMUPS/Shoot-Em-Ups). I have arthritis and it's honestly killing my hands when I play these (and SHMUPS are my absolutely favorite games). I'm open to any plug-ins I can try as well which work with GroovyMAME (I don't know if plug-ins areuniversal, or if they only work for regular MAME or what).
10.) Stupid question...I hit a key in the stock MAME frontend and my information panel on the right (which tells you things like the name of the actual .zip/rom), and despite pressing every non-character key on the keyboard (character keys just start searching for that game), I can't get it back for the life of me.
**EDIT** fixed this one too but leaving in in case it helps someone: This is super simple, there's a little dot on the right which you click on and the information window expands. Problem is GroovyMAME is displaying an image WAY wider than my monitor can display (so even under scan didn't make it show) - had to shift the image ALL the way over with my Extron RGB 203 Rxi (with the DDSP dipswitch OFF - which leaves a skew on the top but enables the controls to shift the image at least, which they can't do with DDSP turned on).
11). ArcadeOSD...is there a tutorial on this I'm failing to find? Is it something which is only for GroovyMAME? I can get it up and lock it to the 15khz screen, but don't know what to do with it after that.
I can't bring this up in a game, correct? I tried to edit the "OSD KEYBOARD MAPPING OPTIONS" in mame.ini to be "HOME" to bring it up in-game and it didn't work...that was probably the totally wrong option for this anyway...
BUT, Arcade OSD is supposed to let me change the centering (doesn't seem to be scaling?) for each and every modeline? How do I bring up the test grid? (did this once by accident and can't find the keypress again). I tried to change things like move the image left, and hit "Test", and the image isn't shifting at all so I must be doing it wrong. Any tips on how to use this to fine-tune the different resolutions would be GREATLY appreciated - everything seems to be off. No default settings I can do which will apply to all of them at once? (like the taskbar in Windows is cut off, and the image is shifted to the left - right off the bat for example).
So that's it - thanks again. What I really find amazing about all these questions is I'm pretty darn good at Google (I thought), but either this is really specialized information or I just stink at googling this stuff - as I thought these would be pretty common problems and I'm simply not finding anything which helps... (not YouTube either).